Method of error correction

Claim 1

A method of decoding transmitted digital information signals to correct errors occurring therein as a result of transmission, wherein said information signals are received as blocks of interleaved digital data word signals and are applied to a first decoder as first error-correcting blocks comprised of a plurality of information word signals, a series of first check word signals associated with said plurality of information word signals, and a series of second check word signals associated with said plurality of information word signals, said information word signals and said first check word signals being interleaved, comprising the steps of: decoding the received digital data word signals in said first decoder and correcting the decoded digital information word signals and said first check word signals by generating error syndromes using said second check word signals, the corrected and decoded digital information word signals forming a block of interleaved word signals; tagging a pointer code signal to each of said information word signals of the block of interleaved word signals to represent whether an uncorrected error remains in such word signals; delaying the tagged interleaved word signals of each such block of tagged interleaved word signals in a deinterleaving stage by respective different amounts so as to deinterleave such tagged interleaved word signals into a different arranging order, thereby providing a second error-correcting block; decoding the digital information word signals of each such second error-correcting block in a second decoder by generating error syndromes using said first check word signals, then comparing, for each said second error-correcting block, the number of erroneous word signals as indicated by said pointer code signals with a predetermined value and, if such number is less than said value, correcting said at least one erroneous word signal by said syndromes and said first check word signals, and then clearing the pointer code signals associated with the corrected erroneous word signals, but, if such number exceeds such value, leaving such pointer code signals uncleared and said at leat one erroneous word uncorrected.

Claim 2

A method of decoding transmitted digital information signals to correct errors occurring therein as a result of transmission, wherein said information signals are received as blocks of interleaved digital data word signals and are applied to a first decoder as first error-correcting blocks comprised of a plurality of information word signals, a series of first check word signals associated with said plurality of information word signals, and a series of second check word signals associated with said plurality of information word signals, said information word signals and said first check word signals being interleaved, comprising the steps of: decoding the received digital data word signals in said first decoder and correcting the decoded digital information word signals and said first check word signals by generating error syndromes using said second check word signals, the corrected and decoded digital information word signals forming a block of interleaved word signals; tagging a pointer code signal to each of said information word signals of the block of interleaved word signals to represent whether an uncorrected error remains in such word signals; delaying the tagged interleaved word signals of each such block of tagged interleaved word signals in a deinterleaving stage by respective different amounts so as to deinterleave such tagged interleaved word signals into a different arranging order, thereby providing a second error-correcting block; decoding the digital information word signals of each such second error-correcting block in a second decoder by generating error syndromes using said first check word signals, then comparing, for each said second error-correcting block, the number of erroneous word signals as indicated by said pointer code signals with a predetermined value and, if such number is less than said value, correcting said at least one erroneous word signal by said syndromes and said first check word signals, and then clearing the pointer code signals associated with the corrected erroneous word signals, but, if such number exceeds such value, leaving such pointer code signals uncleared and said at leat one erroneous word uncorrected.